Generally, with an organic EL light-emitting device, transparent electrodes are provided on a glass substrate, an organic EL light-emitting layer is provided thereon, and layers having the functions of both electrodes and reflective films are further formed at a rear surface using aluminum, silver or the like for increasing the amount of light extracted to the outside; light is then extracted out from the glass surface.
On the other hand, there have been trials into using polycrystalline silicon TFTs as an effective driving method in the case of applying a light-emitting device to a display or the like. With this TFT driving method, as conventionally there is again a method in which light is extracted from the TFT substrate side, but in this case the transistors must be placed in gaps between light-emitting parts, and hence there are problems such as the area of the TFT devices being restricted.
One can thus envisage a method in which the transistors are made so as to extend out as far as the regions of the light-emitting parts, and the light is extracted from the opposite side to the substrate (a top emission method). When this method is adopted, it is necessary to form on the TFT substrate reflective films that have both a reflecting function and a function of shielding the transistors from light. Furthermore, these reflective films preferably also function as electrodes.
When forming an organic EL light-emitting layer on these reflective films, unevenness of the surface of the reflective films becomes a problem. The organic EL light-emitting layer is thin, having an overall thickness of approximately 200 nm, and moreover out of the organic EL light-emitting layer, an electron transport layer where electric field concentration occurs is extremely thin at approximately 30 nm. There is thus a problem that if there is severe unevenness on the surface on which the device is formed, then electric field concentration will occur, short-circuiting of the device will occur, and parts where light cannot be emitted (dark spots) will be formed.
When manufacturing a high-quality top emission type organic EL device, it is thus important to form reflective films that have all of a reflecting function, a function of shielding the transistors from light, and an electrode function, and moreover have little surface unevenness.
Moreover, an extremely thin organic EL light-emitting layer as described above is also used in organic EL light-emitting devices in which not active matrix driving using TFTs but rather passive matrix driving is carried out. In the case of carrying out passive matrix driving, it is thus again important to form reflective films having little surface unevenness.